EDP Sciences
Free access
Volume 420, Number 1, June II 2004
Page(s) 173 - 181
Section Galactic structure, stellar clusters and populations
DOI http://dx.doi.org/10.1051/0004-6361:20035634

A&A 420, 173-181 (2004)
DOI: 10.1051/0004-6361:20035634

IR photometric properties of Red Giants in $\omega$ Cen

A. Sollima1, 2, F. R. Ferraro1, L. Origlia2, E. Pancino2 and M. Bellazzini2

1  Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
    e-mail: ferraro@bo.astro.it; s_sollima@astbo4.bo.astro.it
2  Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy

(Received 5 November 2003 / Accepted 27 January 2004)

We present a near-infrared J and K photometric catalog containing more than 73 000 stars in the central region of the giant Globular Cluster $\omega$ Centauri. This is the largest IR data set ever published for this cluster and has been used to completely characterize the morphology and the properties of the Red Giant Branch (RGB). In particular, we concentrated our attention on (i) the anomalous RGB (RGB-a), recently discovered in this cluster and (ii) the RGB of the dominant metal poor population (RGB-MP) in both the infrared (K,J-K) and optical-infrared (K,V-K) color magnitude diagrams. The full set of morphological parameters and photometric indices has been measured and compared with the empirical relations by Ferraro et al. (2000). We find that the detailed photometric properties of the RGB-a are in full agreement with the recent spectroscopic metallicity estimates that place it at the metal-rich extreme of the stellar population mix in $\omega$ Centauri.

Key words: globular clusters: individual: $\omega$ Cen -- stars: Population II -- stars: evolution -- techniques: photometric -- infrared: stars

Offprint request: A. Sollima, s_sollima@astbo4.bo.astro.it

SIMBAD Objects
Tables at the CDS

© ESO 2004